Blast furnace tuyere



,Mmh 23, 1937. J B, HENRY 2,074,507

BLAST FURNACE TUYERE Filed Nov. 30, 1935 INVENTOR 7 Wa 0. M

Patented Mar. 23,1937

UNITED v STATES PATENT OFFICE 4 Claims.

This invention relates to improvements in blast furnace tuyeres, and it is among the objects thereof, to provide a tuyere with a blast passage so formed as to gradually modify the sectional 5 contour of the air blaststream during its passage through-the tuyere forcing a definite sector of the blast stream, as it leaves the tuyre, to have a predetermined direction away from the central axis of the tuyere, maintaining at the same time an unmodified velocity of blast discharge.

Another object of the invention is the formation of the blast passage in part of a tuyere by a circular wall gradually converging towards the central axis of the tuyere, joined with a diverging l5 wall,which diverging wall, with its side joining members, forms a groove in open communication 25 area or capacity.

Still a further object of the invention is to so proportion the capacity of the divergent groove and the angles of convergence and divergence of the blast passage walls that the total cross-sec- 30 tional area of the blast passage (including groove area) at its outlet is equal to or less than the crosssectional area at any point between inlet and outlet. This insures desired maximum discharge velocity and penetration of blast, including the 35 diverted portion.

And still a further object of the invention is to so proportion the angles of inclination of the walls of the blast passage (including the floor of divergent groove) that the inertia of the blast is 40 overcome to the extent of entirely filling the groove with air at the same pressure as the main body of blast. By experimentation, it has been found that the required maximum angle of inclination (from central axis of tuyere) is about 45 20 degrees and that best results are obtained with 10 to degrees inclination.

It is understood that tuyeres in service project into the burden of the furnace, being secured in a horizontal position, placed radially around the 50 circumference of the stack. The lower side of the tuyere, in this service position, is referred to as lower or bottom side.

It is generally recognized in blast furnace practice that the cause of burning the'nose end of a 55 tuyere is due to unfavorable conditions of the furnace burden, resulting in the formation of a dense area directionally below and in contact with the tuyere nose. This dense area prevents the molten metal from descending normally to the hearth and accumulates the iron in a pool, which, 5 when it contacts the tuyere, burns the nose end and destroys its usefulness.

If, therefore, the tuyere blast passage and outlet were constructed to direct a sector of the air blast against this dense area in front of the lower 10 part of. the tuyere, the oxygen bearing air would break same down through combustion, causing this part of the burden of the furnace to become porous and to move downwardly, thus preventing the formation of this dense area that frequently 15 exists" with the use of tuyres having the. conventional type of blast passage and discharge opening.

Patent to Holzworth #1,789,8'70 is directed to a blast furnace tuyere designed to apply a portion of the blast downwardly a substantial distance back from the nose end of the tuyre by providing a slotted passage extending from the axial passage of the tuyre radially downward. Such structures are inefiicient for the purpose intended as there is no provision for forcing the desired portion of the blast through these radial slots.

In accordance with the present invention, these difiiculties are overcome by effecting a progressive reduction of the cross-sectional area of the tuyere passage so as to displace the desired portion of the blast into an opposing relatively long groove, the angle of inclination of which (from the central axis of the tmrre) being small enough that the inertia of the blast stream is overcome and the diverted part of the blast follows definitely, upon discharge, the inclination of the fioor of the groove.

In the accompanying drawing constituting a part hereof in which like reference characters designate like parts:

Fig. 1 is a vertical cross-sectional view, line l-l, Fig. 2, of an improved hollow water cooled blast furnace tuyere having a divergent groove embodying the principles of this invention;

Fig. 2 a front elevational view thereof;

Fig. 3 a vertical section on line 3-3, Fig. 4, of amodified form of the invention.

Fig. 4 a front elevational view of the ttwere of Fig. 3:

Fig. 5 a vertical cross-sectional view taken along the line 5-5, Fig. 6, of another modified form of tuyere embodying the principles of this invention;

Fig. 6 a front or nose end elevational view thereof; and 55 Fig. 7 a horizontal cross-sectional view taken along the line 1-1, Fig. 6.

With reference to Figs. 1 to 2 inclusive of the drawing, the structure therein illustrated comprises a hollow tuyre I of frusto-conical shape,

having an inner wall 2 forming a main passage 3.

I as a part of the blast passage, the groove extending a substantial distance from the approximate 45 closed in the patent to Holzworth. The structure center longitudinally of the nozzle, the grooved passage having a relatively slight inclination for the displacementthrou'gh it of a definite portion of the blast. To'provide for definite displacement of the blast through the groove 1, the inner wall 2 of the'tuyere' is of gradually reducing diameter to provide a progressively reducing cross-sectional area for the passage of the blast, it being desirable that the combined areas of the nose end and groove are no greater than the area at ":r-x, at which point the modification of the sectional area of the blast stream starts.

In the hereinbefore mentioned prior art structures, the slot at the discharge end of the tuyere was ineffective to direct the blast'as it was nonconflning and was not so proportioned with the tuyere passage to cause displacement of a portion of the blast therethrough.

In the design shown in Figs. 1 and 2, the total area of the main blast passage 3 and the groove I at the discharge end 'is preferably less but no greater than the area of the blast passage at any other point in the tuyere, with the result that there is no expansion of the blast stream (with attending loss of velocity).

The modified form of slot 10. shown in Figs. 3 and 4 is desirable when the outside diameter of the nose end of the tuyere is unusually small. In 'Fig. 3 the groove Ia, extends downwardly below the nose end of the tuyre as in the structure disof Fig. 3 herein differs from that of the prior art in that the entire blast passage is progressively constricted so that section area at yy is equal to or less than the area at any other point in the 50 passage, thus forcing a definite displacement through groove Ia.

The form of blast passage shown in Figs. 5 to 7 inclusive of the drawing may be required in some applications. When it is considered that the blast 5 inlet diameter is fixed while the desired discharge area varies greatly, the advantage of this form of construction is obvious for small capacity tuyeres, so that the proper angle of divergence of the bottom of the groove may be secured.

As shown in Fig. 6, the groove i0 is of greater width than the groove 1 in Fig. 2, and the groove of Fig. 2 is of greater depth than groove Ill of Fi 5.

Thus it is seen that modifications may be made I 65 in the shape of the tuyere passage as well as in the width and depth of the divergent groove to carry out the same principle, i. e., the displacement of a portion of the blast into the divergent groove area to discharge, oxygen-laden air to the furnace burden directly. adjacent the tuyere and in line with the groove to prevent the accumulation of molten metal and the burning-out of the tuyere as is common with the conventional form of tuyre construction.

The inclination of the divergent groove may vary within certain limits in accordance with the degree of convergence of the main blast passage, but the angle of inclination of the divergent groove from the axis of the tuyre should be substantially oblique and materially lesstli'an 45", as. itwould be impossible or impractical to divert the desired portion of the blast through an angle of substantial degree, on account of the inertia of the high velocity blast used in the art.

Although several embodiments of the invention have been herein illustrated and described, it will be apparent to those skilled in the art that various modifications may be made in the details of construction without departing from the principles herein set forth.

I claim:

1. A blast furnace tuyere comprising a body having a main passage of gradually reducing cross-section toward the nose of the tuyre for the transmission of air anda joining divergent groove communicating with said main passage progressively reducing in cross-sectional area from the nose of the tuyere to the rear thereof so that the combined area of the main passage and divergent groove will be no greater at the outlet end of the passage than at any point between inlet and outlet.

2. A blast furnace tuyere comprising a body having a main air passage therein of gradually reducing cross-section toward the nose of the tuyere and having a divergent auxiliary passage communicating with the main air passage from substantially the center of the length of saidair passage to the nose end of the tuyere, said auxiliary passage, through its entire length, being in open communication with the main air passage and of progressively increasing cross-sectional area toward the nose of the tuyre while the main air passage is of progressively decreasing cross-sectional area.

3. A water-cooled blast furnace tuyere comprising a hollow body having a main air passage of constant or progressively decreasing crosssectional area from the air inlet to the outlet thereof, a divergent passage in open communication with said main air passage and of pro.-

clination and width of said divergent passagebeing such that the combined main air passage and the divergent passage area is progressively reducing in the direction of the air inlet to the air outlet of the passage.

J OHN B. HENRY. 

